On 08/05/20 17:32, Peter Xu wrote: > On Fri, May 08, 2020 at 12:33:57AM +0200, Paolo Bonzini wrote: >> On 07/05/20 21:28, Peter Xu wrote: >>>> - svm->vcpu.arch.dr6 = dr6; >>>> + WARN_ON(svm->vcpu.arch.switch_db_regs & KVM_DEBUGREG_WONT_EXIT); >>>> + svm->vcpu.arch.dr6 &= ~(DR_TRAP_BITS | DR6_RTM); >>>> + svm->vcpu.arch.dr6 |= dr6 & ~DR6_FIXED_1; >>> I failed to figure out what the above calculation is going to do... >> >> The calculation is merging the cause of the #DB with the guest DR6. >> It's basically the same effect as kvm_deliver_exception_payload. > > Shall we introduce a helper for both kvm_deliver_exception_payload and here > (e.g. kvm_merge_dr6)? Also, wondering whether this could be a bit easier to > follow by defining: It would make sense indeed but I plan to get rid of this in 5.9 (so in about a month), as explained in the comment. Paolo
